Many years ago when I was in my early twenties I separated my left shoulder. Initially I did it by trying to rip apart those six pack beer holders, you know the plastic ones? I had two of them at the time. Anyhow continue to have trouble for a few years every time I put my left arm over my head at a certain angle it would pop out. For years I would just pop it back in. But then I went skiing with some friends of mine and popped it out real bad. Couldn't get it back in for like a half an hour. Finally I went to the Washington Redskins orthopedic surgeon named Stan Levine. He did the surgery on that shoulder in 1987 I think. They called it a Puti Plat ??? Reattach the ligaments and tenands and made them shorter. Yes it was a very long recovery couldn't raise my arm for almost 2 months. Then the rehab process. But that was 40 years ago. I can still tell I had an issue there but I don't have any issues doing work overhead or working out.